Safety Device For A Pre-Filled Injection Syringe

ABSTRACT

A safety device for an injection syringe including a syringe support, a protective sheath for protecting an injection needle carried by the injection syringe, the protective sheath being mounted to slide relative to the syringe support between an injection position in which the needle is uncovered, and a protection position in which the needle is covered, the protective sheath having an initial grip surface enabling the device to be gripped by a user, the initial grip surface being a projection that extends outward from the protective sheath, and a return spring for urging the sheath into the protection position. The sheath also includes an extender member for extending the initial grip surface, being a separate piece from the protective sheath, attached to the protective sheath in such a manner as to present an enlarged grip surface, larger than the initial grip surface.

FIELD OF INVENTION

The present invention relates to the field of injecting substances suchas medication. It relates more particularly to the field of safetydevices for pre-filled injection syringes.

BACKGROUND OF THE INVENTION

A safety device for an injection syringe is already known that has aprotective sheath that is triggered at the end of injection so as tocover the injection needle and thus avoid any contamination. An exampleof such a device is described in document FR 2 922 112.

Generally, such a device has flanges, or a collar, serving as a bearingsurface for the fingers of the user performing the injection.

A difficulty lies in the fact that those grip flanges can be too smallfor people suffering from inflammatory joint pain or who have difficultyin manipulating or in applying sufficient force on items of small size,for example people suffering from rheumatoid arthritis.

SUMMARY OF THE INVENTION

A particular object of the present invention is to provide a safetydevice that is easier to manipulate, in particular for users whoencounter difficulties in gripping the device.

To this end, the invention provides a safety device for an injectionsyringe, the safety device comprising:

a syringe support;

a protective sheath for protecting an injection needle carried by thesyringe, the sheath being mounted to slide relative to the syringesupport between an injection position in which the needle is uncovered,and a protection position in which the needle is covered, the sheathhaving a grip surface enabling the device to be gripped by a user andreferred to as the “initial” grip surface; and

a return spring for urging the sheath into the protection position; thesheath further includes an extender member for extending the initialgrip surface and fitted on the sheath in such a manner as to present alarger grip surface, referred to as an “enlarged” grip surface.

Thus; it is proposed to add an element to the sheath suitable for makingthe device easier to grip. In such circumstances, it may be advantageousto fit an additional element on the sheath in order to enlarge aninitial grip surface rather than to make a large grip surface directlyon the sheath. Since it is observed that only some users need a largesurface, it is proposed herein to use a device that is standard, for useby users of all types, with the possibility of adapting the safetydevice to certain users, by adding the extender member to the device. Asa result, manufacture is simplified, since a syringe support and asheath are used that are identical to those used in the past, and thusthe same mold can be used, while also providing a guarantee that peoplewho have difficulty in manipulation can use the device withoutdifficulty, because of the possibility of fitting the extender member onthe sheath. In addition, it becomes possible to conserve a grip surfacearea that is relatively small for most users, i.e. to conserve theinitial surface provided on the sheath, thereby making it possible toreduce the general size of the safety device and thus to save space forstorage and transport of the devices.

It should be observed that the injection syringe is preferablypre-filled and is generally a glass syringe, of standard shape and size,e.g. a 0.5 milliliter (mL) or a 1 mL syringe. The syringe is of tubularshape, presenting an injection needle at its distal end, possiblymounted on a fastener endpiece often referred to as a “luer” lock, andpresenting a collar at its proximal end, which collar is made integrallywith the body of the syringe. The collar of the syringe serves inparticular to fasten the syringe on the syringe support, e.g. bysnap-fastening. It should also be observed that the syringe support isgenerally made of plastics material, thus providing the advantage ofmaking the functional portions more easily by making them on the supportrather than on the syringe, which is made of glass. For example, thesyringe support may carry lugs for snap-fastening with the collar of thesyringe, guide elements for guiding the sheath to its protectionposition, locking elements for locking the device in the protectionposition, and/or retractable elements for preventing the device frommoving while in the injection position. It should also be observed thatthe sheath is generally a part made of plastics material and thatperforms several functions. The sheath may include one or more of thefollowing elements: retractable means for compressing the spring to holdthe device in the injection position; guide means for guiding the sheathwhile it is moving to the protection position; means for preventing thesheath from moving while in the protection position; and a tubularportion for covering the needle and for preventing a user's finger fromtouching the needle once the device is in the protection position.

The enlarged grip surface is preferably a surface that covers theinitial grip surface and that extends in a plane substantiallyperpendicular to the axis of the device.

By means of the above-described extender member, the inventors proposetaking an additional step towards standardizing manufacturing methods;not only is it possible to use a standard glass syringe, but it is alsopossible to a use a standard sheath that can be used by users of alltypes, possibly after an extender member has been added.

The safety device of the invention may also include one or more of thefollowing characteristics, taken singly or in combination.

The extender member includes an annular skirt projecting from theenlarged grip surface. This annular skirt is preferably located on thedistal side relative to the enlarged grip surface. It is coaxial aboutthe sheath, being placed around the sheath, and it may perform afunction of centering the extender member on the sheath, by holding theenlarged grip surface in position on the axis of the sheath and thuspreventing it from moving away from the axis as a result of the usermoving in asymmetrical manner on one side of the grip surface. Theannular skirt may also act as a support for a label that providesinformation about the medication to be found in the syringe. Theadvantage of the tubular skirt is that it does not present any portionsin relief, unlike a sheath, which may for example carry clips forpreventing the sheath from moving when in the protection position, thusmaking it relatively unsuitable for receiving a label. The annular skirtmakes it possible to present a surface area free of portions in reliefthat is relatively large, and ideal for carrying a label.

The spring is in a compressed configuration when the sheath is in theinjection position, and the annular skirt is a skirt for masking thespring in the compressed configuration. Often, the sheath and thesyringe support are made of a material that is transparent ortranslucent, so as to enable the user to see the contents of the syringethat is located inside the device. As a result, the user generally alsosees the spring of the safety device. However, the spring is usually apart that is made of metal and can thus give users negativepreconceptions about the sterility of the injected substance or thecleanliness of the system. Although the spring never comes into contactwith the injected substance, it gives a general impression of being adevice that is technical and “not hygienic”. By hiding it by means of anopaque annular skirt, the user is given the impression that the safetydevice is more sterile or cleaner.

The sheath includes means for preventing the sheath from moving in theprotection position, preferably snap-fastener means, and the annularskirt covers these means for preventing the sheath from moving. Theannular skirt thus makes it possible firstly to mask the means forpreventing the sheath from moving, thus improving its appearance, andsecondly makes these means more difficult for the user to access,thereby preventing the safety device from being re-used once it hastaken up its protection position. This advantage is particularlyadvantageous for preventing used devices being re-used and/or forreducing any risk of injury. Furthermore, the skirt thus presents aneven larger surface area suitable for carrying a label.

The annular skirt extends in the longitudinal direction to the distalend of the device, so as to cover all of the needle of the syringe whenthe sheath is in the protection position. In addition to the fact thatthe annular skirt is capable of presenting a very large surface area forcarrying a label, this can enable the extender member to perform thefunction of covering the needle in the injection position and therebysimplify the remainder of the sheath by making this function easier toperform, which may be particularly advantageous for enabling theremainder of the sheath to be unmolded. The portion of the sheath thatcovers the needle in the protection position often needs to present areduction in diameter in order to prevent a finger being inserted afterthe safety position has been taken up. This reduction in diameter makesthe sheath difficult to unmold. By making an extender member that coversthe entire needle, it is possible to reduce the length of the initialsheath and thus to avoid the need of providing this reduction indiameter, thereby making it easier to unmold.

The annular skirt comprises a main tubular portion and a distal end ofdiameter that decreases relative to that of the main tubular portion. Inother words, the distal end of the tubular portion is of tapering shape.

The enlarged grip surface presents two opposite radial ends, these endsbeing curved towards the distal end of the device. The curved ends makegripping the device easier for users who have difficulties, inparticular because it prevents the device from escaping from the hand.

The enlarged grip surface presents anti-skid portions in relief, e.g.ribs.

The enlarged grip surface is made out of a material that is softer thanthe remainder of the safety device, or is covered completely or in partwith such a material. This softer material provides more comfort whengripping the safety device, in particular for users having skin thatmight be sensitive to sharp edges.

The device includes snap-fastener means for snap-fastening the extendermember to the sheath and carried by the extender member and/or by thesheath. These means are carried in particular by the initial grip wallof the device.

The enlarged grip surface presents two opposite radial ends that areconnected together by two sides, each presenting a flat. These flatsenable the device to be oriented during the method of manufacturing thedevice, and they also make it easier to store, preventing the devicefrom rolling.

The sheath and the support are made of a material that is translucent ortransparent, and the extender member is made of a material that isopaque. The extender member thus serves to hide certain elements. Inaddition, it may serve as means for indicating the type of medicationthat is to be found in the syringe. For example, it may be of a colorthat indicates the kind of medication that is in the syringe, or indeedthe syringe capacity, or the filling percentage of the syringe.

The extender member is put into place via the distal end of the device.Thus, there is no danger of the user separating the extender member fromthe sheath when injecting the substance, i.e. when pressing on theextender member while directing a force towards the proximal end of thedevice.

The device includes a tamperproofing sleeve fastened to the device by abreakable connection, preferably integrally molded with the extendermember. This makes it possible to ensure that the device has not beenopened prior to injection.

The invention also provides a set of two devices as described above,each presenting a syringe support and a sheath that are identical inboth devices and respective extender members for extending the gripsurface that are different from one device to the other. For example,the extender members may be of different shapes, colors, and/ormaterials, thus making it possible to distinguish between differenttypes of safety device, of syringe, or of medication. Possibly, one ofthe devices has an extender member while the other device does not haveone at all.

The invention also provides an assembly of a device as described abovetogether with a pre-filled syringe. The syringe is preferably made ofglass and has a collar integrally formed with the syringe body. Thecollar of the syringe is an element distinct from the initial gripsurface and from the enlarged grip surface.

The invention also provides a method of assembling a device as describedabove, in which method a portion of the sheath is initially assembledwith the support, after which the extender member is fitted to saidportion of the sheath, preferably via the distal end of the sheath.

This assembly method is preferably followed by a step of assembling apre-filled syringe in the safety device.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention can be better understood on reading the followingdescription given purely by way of example and made with reference tothe drawings, in which:

FIGS. 1a and 1b are longitudinal section views of the assemblycomprising a safety device and a syringe in a first embodiment, shownrespectively in the injection position and in the protection position;

FIGS. 2a and 2b are perspective views, respectively from above and frombelow of a portion of the FIG. 1a assembly;

FIG. 3 is a perspective view of an extender member for a safety devicein a second embodiment;

FIG. 4 is a perspective view of an extender member for a safety devicein a third embodiment;

FIG. 5 is a longitudinal section view of a sheath of a safety device ina fourth embodiment;

FIG. 6 is a perspective view of the assembly of a safety device and asyringe in a fifth embodiment;

FIG. 7 is a perspective view of the assembly of a safety device and asyringe in a sixth embodiment;

FIG. 8 is a view similar to FIG. 1a of an assembly in a seventhembodiment;

FIG. 9 is a view similar to FIG. 1a of an assembly in an eighthembodiment; and

FIG. 10 is a view similar to FIG. 1a of an assembly in a ninthembodiment.

DETAILED DESCRIPTION OF THE INVENTION

FIGS. 1a, 1b, 2a, and 2b show an assembly 10 of a safety device 11 andan injection syringe 12. The safety device 11 comprises a syringesupport 14, a protective sheath 16, and return means 18. The sheath 16is mounted to slide relative to the support 14 between an injectionposition and a protection position, under drive from the return means18, constituted in this example by a spring in compression.

The syringe 12 is a glass syringe, pre-filled with a substance. Thesyringe 12 is a standard glass syringe, e.g. a 0.5 mL or a 1 mL syringe.It comprises a glass body defining a container for the substance andcarrying at its distal end an injection needle 20, possibly connectedvia a luer lock. When the device 11 is in the injection position, theneedle 20 is uncovered, i.e. it is visible to the user, and when thedevice 11 is in the protection position, the needle 20 is covered by thesheath 16, so as to prevent accidental pricking after injection. Theglass syringe body also includes a collar 22 at its proximal end, whichcollar is made integrally with the syringe body. The collar 22 serves inparticular to fasten the body of the syringe 12 on the support 14. Thesyringe 12 also includes a piston 24 having an elastomer base 26, a rod28, and a plunger 30. The piston 24 is mounted to slide in the syringebody so as to be capable of injecting the substance contained in thesyringe body.

The syringe support 14 is a plastics material part that is generallytubular in shape. At its proximal end, it carries snap-fastener means 32for permanently engaging the collar 22 of the syringe on the support 14.In this example, the means 22 comprise lugs distributed angularly aroundthe longitudinal axis X of the device so as to form an abutment in thedirection X and prevent the collar 22 from moving between the lugs and acircular seat made on the support 14. The support 14 extends from theproximal end of the syringe body 12 to the vicinity of its distal end.More precisely, the support 14 allows the distal end of the syringe body12 to project a little, as can be seen in FIG. 1a . The support 14 alsoincludes an abutment 34 for retaining the syringe support in theinjection position, and an abutment 36 forming a seat for the spring 18.The abutments 34 and 36 are arranged on the proximal end of the support14. The support 14 also includes means 38 for preventing the supportfrom moving relative to the sheath 16 when in the protection position,which means are arranged on the distal end of the support 14. Moreprecisely, the means 38 compromise lugs that become inserted in slots inthe sheath 16 once the device is in the protection position, under drivefrom the spring, so as to prevent the support 14 from moving relative tothe sheath 16. The support 14 also includes fluting in a portion of itstubular outside surface, which fluting extends in the longitudinaldirection X and serves to guide the sliding of the support 14 relativeto the sheath 16 while these two parts are being assembled together, andwhile the sheath is moving into the protection position.

The protection sheath 16 is a plastics material part of generallytubular shape. In this invention, it comprises two parts that are fittedtogether. More precisely, the sheath 16 comprises a part 40 that isreferred to below as the “initial” sheath 40, and an extender member 42for extending the initial extension surface. The initial sheath 40 is asheath that, in this example, is capable of being used on its own as thesheath of the device 11, the member 42 not being essential for itsoperation. In particular, the initial sheath 40 has a grip wall 43carrying a grip surface 44 enabling a user to grip the device 11, andreferred to as the “initial” grip surface. This initial surface 44 is asurface located at the distal end of the wall 43, it extends in a radialplane substantially perpendicular to the longitudinal axis X, and itincludes at least two diametrically opposite portions in the form ofgrip flanges. The initial surface 44 may also be in the form of acircular collar extending around the initial sheath 40 and lying in aradial plane. The initial surface 44 is configured in such a manner thatin order to inject the substance contained in the syringe 12, the userengages two fingers, generally the index and middle fingers, under thesurface 44 on either side of the axis X, and places the thumb on theplunger 30 in order to move the piston 24. The member 42 enables thedevice 11 to be adapted to some particular utilization in which it isnecessary to have a grip surface that is larger than usual. To this end,the member 42 has a wall 45 presenting a surface 46 on its distal sidethat is referred to as the “enlarged” grip surface and that is fitted onthe initial surface 44 in such a manner that the device 11 presents agrip surface that is larger than the initial surface 44. In thisexample, the enlarged surface 46 completely covers and enlarges theinitial surface 44. As can be seen in FIGS. 1a and 1b , the surface 46presents a length in the radial direction that is greater than thecorresponding length of the initial surface 44. The member 42 isfastened on the initial sheath 40 by snap-fastener means 48, comprisingin this example lugs 48 that extend from the top (or proximal surface)of the wall 45 carrying the enlarged grip surface 46. The means 48enable the member 42 to be snap-fastened on the initial sheath 40, andmore precisely on the initial grip wall 43. It should be observed thatthe enlarged grip surface 46 presents anti-skid portions in relief 50.Furthermore, as can be seen in FIG. 2a , the enlarged grip surface 46presents two opposite radial ends 49 that are connected together by twosides 51, each presenting a respective flat and making it easier toorient the device 11 during assembly, transport, and storage.

The protective sheath 16 also includes certain functional portions,which are carried by the initial sheath 40 in this example.

More precisely, the sheath has a distal end 52 arranged to prevent aperson's finger coming into contact with the needle when the sheath 16is in the protection position. For this purpose, the end 52 presents areduction in diameter to prevent a finger being inserted inside thesheath 16. In this example, the end 52 is split so as to present“petals” that enable the initial sheath 40 to be unmolded as a result ofthe elasticity of the petals. The sheath 16 also includes retainingmeans 54 for retaining the device in the injection position, the means54 being retractable when the piston reaches the end of its stroke,thereby triggering the movement into the protection position. Moreprecisely, the means 54 comprise lugs at the proximal end of the device11 and extending radially inwards so as to retain the abutments 34. Thesheath 16 preferably has two diametrically opposite lugs 54, eachcarried by a resilient tab presenting a ramp 56 co-operating with thepiston 24 so that the lugs 54 are spaced apart outwards and thus nolonger retain the abutments 34 when the piston reaches the end of itsstroke.

Furthermore, the sheath 16 presents means 58 for preventing the sheathfrom moving when in the safety position, which means 58 co-operate withthe means 38 provided on the support 14. In this example, the means 58comprise two diametrically opposite slots defined in particular by tworesilient tabs 60 capable of moving radially so that the lugs 38 can beforced past them under drive from the spring so as to snap into theslots 58.

The sheath 16 also has an abutment surface 62 forming a seat for thedistal end of the spring 18. The surface 62 is defined by the end of agroove for receiving the spring 18, serving to center the spring whilethe device 11 is being assembled. It should be observed that the insidewall of the groove 62 is not annular, but comprises two diametricallyopposite portions spaced apart by a gap making it possible for the guidefluting of the support 14 to slide relative to the sheath 16.

In this example, the extender member 42 comprises an annular skirt 64projecting from the enlarged grip surface 46, and thus located on thedistal side of the member 42. The skirt 64 serves to center the extendermember 42 on the initial sheath 40. In addition, the annular skirt 64 isa skirt for masking the spring 18 in the compressed configuration. Theinitial sheath 40 and the support 14 are preferably made of atransparent material, while the member 42 is made of an opaque material,so that the skirt 64 serves to hide the spring while it is compressed.

The operation of the assembly 10 shown in FIGS. 1a, 1b, 2a , and 2 b isdescribed below.

When the user seeks to perform an injection, the device is in theinjection position, i.e. the sheath 16 does not cover the needle, asshown in FIG. 1a . In principle, the needle should be covered by a capthat the user removes in order to begin the injection. The needle 20 isthen inserted into the user's body or into the body of a patient andinjection is begun by the thumb pressing down on the piston 24 while twofingers are engaged under the enlarged grip surface 46. Once thesubstance has been fully injected into the patient's body, the pistonreaches the end of its stroke, and the bottom end of the plunger 30co-operates with the ramps 56 so as to move the lugs 54 apart andrelease the spring 18 so that it can relax. As it decompresses, thespring 18 pushes against the surface 36 of the syringe support 14 sothat the support 14 and thus the syringe 12 slide relative to the sheath16 moving “upwards” relative to the sheath 16 in order to reach aprotection position, as shown in FIG. 1b . In this protection position,the needle 20 is completely covered by the sheath 16 and it is notpossible to make contact with the needle since it is not possible topass a finger through the end 52. Furthermore, the device 11 is lockedin this protection position by the means 38 and 58 that prevent thesheath 16 from sliding relative to the support 14.

One example of assembling the device 11 comprises the following steps.The device 11 is initially put together and pre-assembled without thesyringe 12, such that the syringe can be manufactured independently ofthe device 11. This is particularly advantageous: the laboratory thatmanufactures the medication for injection can thus fill the syringe 12and can itself fit it in the pre-assembled device 11, merely byinserting the syringe and without any need to use a relatively complexmachine for assembling the device 11. That assembly is performeddirectly by the manufacturer of the device 11 in a different factory.The manufacturer of the device 11 begins by injection molding theelements 40, 42, and 14. Thereafter, the spring 18 is fitted inside theinitial sheath 40 via the proximal end of the sheath 40 by beinginserted into the groove 62, and then the support 14 is inserted insidethe sheath 40 and the spring 18. By pressing on the support 14, thespring 18 is compressed until the abutments 34 of the support 14snap-fasten with the lugs 54 of the sheath 40. This produces a devicehaving a pre-compressed spring, and having a relatively small gripsurface 44 that is directly usable as such. In order to enable thedevice 11 to be used with greater comfort, it is possible to fit theextender member 42 for extending the grip surface. Under suchcircumstances, the member 42 is inserted via the distal end of theinitial sheath 40 and the means 48 snap-fasten on the initial grip wall43. This provides a fully assembled device 11 including thepre-compressed spring 18, suitable for the device 11 to be transportedto a laboratory where the pre-filled syringe 12 can be assembled in thedevice 11 merely by inserting the syringe through the proximal end ofthe device 11 so as to cause the collar 22 of the syringe to snap-fastenin the elements 32, and without any need to provide an assembly machinesuitable for compressing the spring.

Other embodiments of the member 42, similar to the embodiment describedabove, are shown in the figures.

In FIG. 3, the snap-fastener means 48′ do not project from the enlargedgrip wall 45 but are housed inside a recess formed in said wall 45, soas to avoid projecting beyond the proximal surface of the wall 45, forreasons of improved appearance. Furthermore, in FIG. 3, there can beseen the inside orifice of the annular skirt 64 with projecting elements70 for positioning the member 42 around the initial sheath 40. In FIG.4, the snap-fastener means 48″ are slightly different from the means 48in FIG. 1a . They comprise lugs extending radially from the proximalsurface of the wall 45, without projecting beyond said wall in thelongitudinal direction X, thereby making them more discreet than thelugs 48.

In FIG. 5, the annular skirt 64′ extends in the longitudinal directionover a greater distance than the skirt 64. It may thus serve as a largersupport for a label. In addition, and in particularly advantageousmanner, the skirt 64′ covers the means 38 and 58 for preventing thesheath 16 from moving relative to the support 14, thereby serving tomask them and to make them inaccessible, and thus serving to prevent thedevice 11 from being reactivated. The annular skirt 64′ extends in thelongitudinal direction X to the distal end of the device 11 so as tocover all of the needle 20 of the syringe when the sheath 16 is in theprotection position. More precisely, the annular skirt 64′ comprises amain tubular portion 72 and a distal end 74 of diameter that decreasesrelative to the diameter of the main tubular portion 72 in order toprevent a finger being inserted. In this embodiment, the initial sheath40′ does not have the end 52 of the initial sheath 40 of FIG. 1b , withthe diameter-reduction function being provided by the skirt 64′.

In FIG. 9, the annular skirt 64′ is substantially the same as in FIG. 5,and the initial sheath 40 is substantially the same as in FIG. 1b . Inparticular, the initial sheath 40 has the tapering end 52 for preventinginsertion of a finger. This end 52 is covered by the tapering end 74 ofthe skirt 64′, thereby providing even better protection of the needleonce used.

In FIG. 10, the device is substantially the same as in FIG. 9. Thetapering end 74 of the annular skirt 64′ is extended by a closed sleeve76 that covers the needle 20 and that is referred to as the“tamperproofing” sleeve, which sleeve is fastened to the device by meansof a breakable connection so as to enable the user to verify that thedevice has not been opened prior to injection. More precisely, theextender member 42 is molded integrally with the tamperproofing sleeve76, the sleeve 76 being connected to the annular skirt 64′ by breakablebridges 80 that are distributed around the circumference of the sleeve76, between the sleeve 76 and the tapering end 74 of the annular skirt64′. The needle 20 is also protected by a removable cap 78. In addition,the fastener lugs 48 of the member 42 on the initial sheath 40 providetamperproof fastening of the member, i.e. once the member 42 has beenseparated from the sheath 40 they do not allow the member 42 to befastened once more on the sheath 40: separation of the member 42 is notreversible.

Prior to utilization, it is thus very easy to verify that the device hasnot been opened. In order to perform an injection, the user breaks thebridges 80 to separate the sleeve 76 from the skirt 64′ and takes awaythe cap 78 so as to lay bare the needle 20. Once the bridges 80 havebeen broken, it is not possible to fasten the sleeve 76 once more on theannular skirt 64′.

In FIG. 8, the annular skirt 64′ does not extend to the distal end ofthe safety device, unlike in FIGS. 5 and 9. Nevertheless, it extendsover a relatively long distance around the initial sheath 40, a distancethat is sufficient to cover the means 38 and 58 for preventing thesheath 16 from moving relative to the support 14, so as to mask thosemeans and make them inaccessible. In addition, the surface area of theskirt 64′ is large enough and smooth enough to be used as a support fora label.

In FIG. 6, the extender member 42 does not present an annular skirt 64.

In FIG. 7, the enlarged grip surface 46 presents two opposite radialends 49′, these ends being curved towards the distal end of the device11.

It can be understood that the above-described extender member 42 enablesthe safety device to be manufactured with a size that is substantiallystandard, comprising the elements 40, 18, and 14, while still beingcapable of being adapted to a special utilization by adding the member42. It is thus possible to customize the safety device 11. Inparticular, different extender members 42 may be provided from onedevice 11 to another, which members may be made with different colors,materials, or shapes.

It should be observed that the invention is not limited to theabove-described embodiments. In particular, the characteristics of thevarious embodiments may naturally be combined with one another, or theymay be used separately.

What is claimed is:
 1. A safety device for an injection syringe, thesafety device comprising: a syringe support; a protective sheath forprotecting an injection needle carried by the injection syringe, theprotective sheath being mounted to slide relative to said syringesupport between an injection position in which the needle is uncovered,and a protection position in which the needle is covered, the protectivesheath having an initial grip surface enabling the device to be grippedby a user, the initial grip surface being a projection that extendsoutward from the protective sheath; and a return spring for urging theprotective sheath into the protection position; wherein the protectivesheath also includes an extender member for extending the initial gripsurface, being a separate piece from the protective sheath, attached tothe protective sheath in such a manner as to present an enlarged gripsurface, larger than the initial grip surface.
 2. The device accordingto claim 1, wherein the projection extends outward from the protectivesheath in a radial plane substantially perpendicular to a longitudinalaxis of the device.
 3. The device according to claim 1, wherein theextender member comprises an annular skirt projecting from the extendermember.
 4. The device according to claim 3, wherein the spring is in acompressed configuration when the protective sheath is in the injectionposition, and wherein the annular skirt masks the spring in thecompressed configuration.
 5. The device according to claim 3, whereinthe protective sheath includes a mechanism for preventing the protectivesheath from moving in the protection position, and the annular skirtcovers said mechanism for preventing the protective sheath from moving.6. The device according to claim 5, wherein the mechanism for preventingthe protective sheath from moving in the protection position is asnap-fastener.
 7. The device according to claim 5, wherein the mechanismfor preventing the protective sheath from moving in the protectionposition is slots which engage with lugs on said syringe support.
 8. Thedevice according to claim 3, wherein the annular skirt extends in alongitudinal direction to a distal end of the device, so as to cover allof the needle of the syringe when the protective sheath is in theprotection position.
 9. The device according to claim 8, wherein theannular skirt comprises a main tubular portion and a distal end with adiameter that decreases relative to a diameter of the main tubularportion.
 10. The device according to claim 1, wherein the extendermember has two opposite radial ends, said ends being curved towards thelongitudinal axis and a distal end of the device.
 11. The deviceaccording to claim 1, wherein the enlarged grip surface includesanti-skid portions.
 12. The device according to claim 1, wherein theextender member has two opposite radial ends that are rounded andconnected together by two opposite flat sides.
 13. The device accordingto claim 1, including a tamperproofing sleeve fastened to the device bya breakable connection.
 14. The device according to claim 13, whereinthe breakable connection is integrally molded with the extender member.15. An assembly of the safety device according to claim 1 and theinjection syringe comprising a pre-filled syringe.
 16. A method ofassembling the device according to claim 1, wherein a portion of theprotective sheath is initially assembled with said syringe support,after which the extender member is fitted on said portion of theprotective sheath.
 17. The device according to claim 1, wherein theextender member surrounds an outer edge of the initial grip surface. 18.The device according to claim 1, wherein the extender member engages anouter edge of the initial grip surface.
 19. The device according toclaim 1, wherein the extender member includes a cavity which receivesthe initial grip surface and extends around an outer edge of the initialgrip surface.
 20. The device according to claim 1, wherein the initialgrip surface comprises at least two diametrically opposite portions in aform of grip flanges.
 21. The device according to claim 1, wherein theinitial grip surface is in a form of a circular collar extending aroundthe protective sheath and lying in the radial plane.